The invention relates to ink jet printing devices and more particularly to ink jet printers using a customer replaceable printhead assembly having an electronic monitoring system to record and display the amount of use or lifetime remaining for the installed printhead assembly.
For the convenience of the users or customers of ink jet printers, customer replaceable printheads are used which may be removed and replaced by the customer when the printhead's design lifetime has expired. The customer replaceable printheads also use customer replaceable ink supply tanks or cartridges, and each printhead may deplete the ink from many ink cartridges before reaching the end of its design lifetime. For existing multicolor ink jet printheads, it is not uncommon for the printhead to deplete the ink from as many as ten ink cartridges for each color, for example, yellow, magenta, cyan, and black, before reaching the end of the printhead lifetime. However, the customer tends to lose track of the remaining lifetime of the printhead when the replaceable cartridges are replaced a number of time and does not know when to replace the printhead. This can be a serious problem. Another problem occurs when the printhead is returned under a service warranty, because the manufacturer or supplier has no indication of the amount of use of the customer replaceable printhead, and it is difficult to determine what percentage of the printhead design lifetime has been consumed or if the design lifetime has been exceeded. The confusion over the amount of printhead lifetime consumed could provide a hardship on both the customer and the supplier, for it is difficult to determine if the customer deserves new printhead because the old one did not meet warranty or whether the printhead has been used up and the customer should purchase a new one.
U.S. Pat. No. 4,961,088 discloses a system for monitoring customer replaceable cartridges in printers or copiers. Each replaceable cartridge includes an electrically erasable programmable read only memory (EEPROM) which is programmed with a cartridge identification number that when matched a cartridge identification number in the printer or copier enables the printer or copier to operate, provides a cartridge replacement warning count, and provides a termination count at which the cartridge is disabled from further use. The EEPROM is programmed to store updated counts of the remaining number of images or prints available by the cartridge after each print or copy is made by the printer or copier.
U.S. Pat. No. 5,021,828 discloses a replaceable unit for use in a copier or printer in which initial use and near-end-of-life is recorded by electrical means, including a portion itself removable from the removable, comprising two fuses. A first fuse is blown when a few copies have been made with the replaceable unit, and the second fuse is used to prevent further use of the replaceable unit when a certain number of copies or prints have been made with the replaceable unit.
U.S. Pat. No. 5,283,613 discloses a monitoring system for replaceable cartridges in a printer or copier, including an electronic count memory and an electronic flag memory. The count memory maintains a one-by-one count of prints made with the cartridge. The flag memory includes a series of bits which are alterable from a first state to a second state but not alterable from the second state to the first state. The bits in the flag memory are altered at predetermined intervals as prints are made with the cartridge. The flag memory is used as a check to override unauthorized manipulation of the count memory.
U.S. Pat. No. 5,365,312 discloses replaceable ink reservoirs, ribbon cassettes, or toner cartridges having an electronic memory means in the form of a chip in which information is stored about the current fill status of the reservoir and other status data that are relevant for printer operation. The used status of the ink or other printing medium is acquired from the controller of the printing machine and is communicated to the chip. The chip on the reservoirs counts consumption until the supply is exhausted to such an extent the reservoir must be replaced. A reprogramming of the chip and refilling of the reservoir is not possible.
Because ink jet printers are typically designed for specifically formulated ink, it is important to know if the correct ink is used. It is damaging to the printheads to attempt to eject an ink droplet when the ink channels are empty, so it is also important to monitor the status of the amount of ink left in the cartridge prior to each attempt to print with it. Solutions to these problems have been sought, but precisely monitoring and feeding back information to the customer or supplier on the amount of the design life which has been consumed for a customer replaceable printhead remains to be solved, especially when many customer replaceable ink tanks have been installed, depleted of ink, and replaced.